NSW Police have activated Operation Stay Alert with double demerits coming into force from Friday morning until Monday night.

More than 2000 incidents have been reported so far. The most serious involved a 36-year-old man who died when his car hit a tree at Yass on Saturday.

During the Queen's Birthday holiday week, police say they are targeting drivers affected by alcohol, drugs and fatigue, as well as mobile phone use and speeding. Some 1100 speeding offences alone have been clocked since the blitz began.

Of more than 32,000 breath tests carried out so far, just 12 resulted in charges for excess alcohol readings.

Among the more unusual incidents was the arrest of a learner driver and his supervisor after testing positive in a breath test at Helensburgh near Wollongong on Friday night. The pair, who were allegedly driving without lights on at the time of the tests, were charged with low- and mid-range drink driving offences.

In a separate incident in Sydney's west on Friday, a driver allegedly crashed his stolen car into several vehicles before fleeing on foot.

The man was arrested as he allegedly attempted to steal a second vehicle. Police say they found the man to have methamphetamine in his possession before he was taken to hospital.

Assistant Commissioner Michael Corboy of the Traffic and Highway Patrol Command called for drivers to be cautious with wet weather forecast for much of the state during the weekend especially in the north-east.

"We have already seen a number of motorists take unnecessary risks on the road this long weekend," Assistant Commissioner Corboy said.

"After the recent wet-weather conditions, we don't want to see an increase in road trauma following the conclusion of this operation," he said. "It's simple: Slow down and stay alert."